Method and system of bit rate control

ABSTRACT

A method and system for bit rate control during encoding of multimedia data are disclosed. A change in complexity of a multimedia picture relative to complexity associated with one or more multimedia pictures in a multimedia sequence is determined. A complexity associated with a multimedia picture is determined based on number of bits and an average quantization associated with the multimedia picture. A bit rate is adjusted for encoding the multimedia picture based on the change in complexity of the multimedia picture. The bit rate is increased on determining an increase in complexity of the multimedia picture and is decreased on determining a decrease in complexity of the multimedia picture. Utilization of additional bits during the increase in the bit rate and saving of bits during the decrease in the bit rate are compensated during adjusting of bit rates for encoding subsequent multimedia pictures in the multimedia sequence.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/901,078 filed Jun. 15, 2020, which is a continuation of U.S. patentapplication Ser. No. 13/303,748, filed Nov. 23, 2011, now U.S. Pat. No.10,728,545, each of which is incorporated herein by reference in itsentirety.

TECHNICAL FIELD

The present disclosure generally relates to the field of data encoding.

BACKGROUND

Pursuant to an exemplary scenario, in multimedia applications, bitsgenerated during the encoding of multimedia data may be minimized whilea perceptual quality of the multimedia data is maximized. Multimediadata may be heterogeneous, implying a varying degree of complexity fromone multimedia picture to another multimedia picture in a multimediasequence. An example of a multimedia sequence is a collection ofconsecutive multimedia pictures with all multimedia pictures in themultimedia sequence belonging to the same or a different scene. Thevariation of complexity may be observed, for example, in the case ofvideo security applications wherein large durations of minimal activitymay occur along with small isolated durations of high activity. Thisresults in a high variation of complexity between the low activity andhigh activity multimedia pictures. Varying degrees ofactivity/complexity renders it difficult to achieve a desired bit rateover the duration of the multimedia sequence. Furthermore, maintainingthe desired bit rate over both the low complexity and high complexitydurations of the multimedia sequence may result in severe multimediaquality degradation.

SUMMARY

Methods and systems for bit rate control during encoding of multimediadata are disclosed. In an embodiment, a method includes determining achange in complexity of a multimedia picture relative to complexityassociated with one or more multimedia pictures in a multimediasequence. In an embodiment, the complexity is determined based on anumber of bits and an average quantization associated with themultimedia picture. In an embodiment, determining the change incomplexity includes determining a local complexity and a globalcomplexity associated with the multimedia picture and comparing thelocal complexity and the global complexity based on a predeterminedcriterion.

The local complexity is determined over a first complexity duration andcorresponds to a complexity associated with the multimedia picture(e.g., a current multimedia picture) and at least one of one or moremultimedia pictures preceding the multimedia picture (e.g., the currentmultimedia picture) and/or one or more multimedia pictures succeedingthe multimedia picture (e.g., the current multimedia picture). Theglobal complexity is determined over a second complexity duration andcorresponds to a complexity associated with the multimedia picture(e.g., the current multimedia picture) and at least one of a pluralityof multimedia pictures preceding the multimedia picture (e.g., thecurrent multimedia picture) and a plurality of multimedia picturessucceeding the multimedia picture (e.g., the current multimediapicture).

In an embodiment, the method further includes adjusting a bit rate forencoding the multimedia data based on the change in complexity of themultimedia picture. In an embodiment, adjusting the bit rate includesperforming one of increasing the bit rate on determining an increase incomplexity of the multimedia picture and decreasing the bit rate ondetermining a decrease in complexity of the multimedia picture. Theutilization of additional bits during a corresponding increase in thebit rate and saving of bits during a corresponding decrease in the bitrate is compensated by adjusting of bit rates for encoding subsequentmultimedia pictures in the multimedia sequence.

In an embodiment, the increase and decrease in the bit rate isproportional to the increase and decrease in the complexity,respectively In an embodiment, additional bits consumed by increasingthe bit rate upon determining an increase in complexity of themultimedia picture are identified and subsequently compensated bydecreasing the bit rate upon determining a decrease in complexity of asubsequent multimedia picture. In an embodiment, the bit rate isdecreased for a duration until all additional bits consumed during theincrease of the bit rate are compensated. In an embodiment, additionalbits saved by decreasing the bit rate upon determining a decrease incomplexity of the multimedia picture are identified. The savedadditional bits are subsequently utilized by increasing the bit rateupon determining an increase in complexity of a subsequent multimediapicture.

In an embodiment, a system for the encoding of multimedia data isprovided. The system includes a complexity determination engine and abit rate engine. The complexity determination engine is configured todetermine change in complexity of a multimedia picture relative tocomplexity associated with one or more multimedia pictures in amultimedia sequence. The complexity associated with a multimedia pictureis determined based on a number of bits and an average quantizationassociated the multimedia picture. The bit rate engine is configured toadjust a bit rate for encoding the multimedia data based on thecomplexity. The bit rate engine is configured to increase the bit rateon determining an increase in complexity of the multimedia pictureand/or decrease the bit rate on determining a decrease in complexity ofthe multimedia picture. The utilization of additional bits during acorresponding increase in the bit rate and saving of bits during acorresponding decrease in the bit rate is compensated by adjusting ofbit rates for encoding subsequent multimedia pictures in the multimediasequence.

Moreover, in an embodiment a computer-readable medium storing a set ofinstructions that when executed cause a computer to perform a method ofbit rate control during encoding multimedia data is provided. In anembodiment, the method includes determining a change in complexity of amultimedia picture relative to complexity associated with one or moremultimedia pictures in a multimedia sequence. In an embodiment, thecomplexity is determined based on a number of bits and an averagequantization associated with the multimedia picture. The method alsoincludes adjusting a bit rate for encoding the multimedia picture basedon the change in complexity of the multimedia picture. In an embodiment,adjusting the bit rate includes performing one of increasing the bitrate on determining an increase in complexity of the multimedia pictureand decreasing the bit rate on determining a decrease in complexity ofthe multimedia picture. The utilization of additional bits during acorresponding increase in the bit rate and saving of bits during acorresponding decrease in the bit rate is compensated by adjusting ofbit rates for encoding subsequent multimedia pictures in the multimediasequence.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a block diagram of a system for encoding multimedia dataaccording to an embodiment;

FIG. 2 is a simplified overview of a process flow illustrating aplurality of states of operation of the system of FIG. 1 according to anembodiment;

FIGS. 3A and 3B illustrate an exemplary scenario of sampling multimediadata for a large complexity duration in a fixed point system accordingto an embodiment;

FIG. 4 illustrates exemplary bit rate traces for encoding multimediadata pursuant to an exemplary scenario;

FIGS. 5A-5D illustrate improvement of a perceptual multimedia quality onadjusting a bit rate based on a change in complexity of a multimediasequence, pursuant to an exemplary scenario; and

FIG. 6 is a flow chart of a method of bit rate control according to anembodiment.

DETAILED DESCRIPTION

Pursuant to an exemplary scenario, a perceptual quality of multimediadata may deteriorate as a result of utilizing a same bit rate ofencoding over both the low complexity and high complexity durations ofmultimedia pictures, especially for multimedia data involving highlyvarying degrees of complexity. Various embodiments of the presenttechnology, however, provide systems and methods of encoding multimediadata that are capable of overcoming these and other obstacles andproviding additional benefits.

The following description and accompanying figures demonstrate that thepresent technology may be practiced or otherwise implemented in avariety of different embodiments. It should be noted, however, that thescope of the present technology is not limited to any or all of theembodiments disclosed herein. Indeed, one or more of the devices,features, operations, processes, characteristics, or other qualities ofa disclosed embodiment may be removed, replaced, supplemented, orchanged.

FIG. 1 is a block diagram of a system 100 for bit rate control duringencoding multimedia data associated with a multimedia picture accordingto an embodiment. Examples of multimedia data include, but are notlimited to, video data, and the like. The multimedia picture may beassociated with a multimedia sequence. Each multimedia sequence mayinclude one or more multimedia pictures (e.g., video pictures). Anexample of a multimedia sequence is a collection of consecutivemultimedia pictures with all multimedia pictures in the multimediasequence belonging to the same or a different scene.

In an embodiment, the system 100 is an exemplary form of a computersystem within which sets of instructions (for example, instructions forcausing system 100 to perform one or more of the methodologies discussedherein) are executed. In various embodiments, the system 100 operates asa standalone device and/or is communicatively associated with, coupledwith or connected to (e.g., networked) other machines, including, forexample, an encoder configured to encode the multimedia data. In oneembodiment, the system 100 is integrated within the encoder. In anembodiment, in a networked deployment, the system 100 operates in thecapacity of a server and/or a client machine in a server-client networkenvironment, and/or as a peer machine in a peer-to-peer (or distributed)network environment.

Examples of the system 100 include, but are not limited to, a multimediaencoding device, a personal computer (PC), a tablet PC, a personaldigital assistant (PDA), a mobile communication device, a web appliance,a set-top box (STB), an embedded system and/or any machine capable ofexecuting a set of instructions (sequential and/or otherwise) to performone and/or more of the methodologies discussed herein. In an embodiment,the system 100 is programmed to comply with a video compressionstandard. Examples of the video compression standards include, but arenot limited to, video coding experts group (VCEG), H.120, H.261, movingpictures experts group (MPEG), MPEG-1 Part 2, H.262 or MPEG-2 Part 2,H.263, MPEG-4 Part 2, H.264 or MPEG-4 AVC, VC-2 (Dirac), high efficiencyvideo coding (HEVC), and the like.

In FIG. 1, the system 100 includes a complexity determination engine102, a bit rate engine 104 and a memory 106. Examples of the memory 106include, but are not limited to, random access memory (RAM), dual portRAM, synchronous dynamic RAM (SDRAM), double data rate SDRAM (DDRSDRAM), and the like. In an embodiment, the complexity determinationengine 102, the bit rate engine 104, and/or the memory 106 areconfigured to communicate with each other via a bus 108.

In an embodiment, the complexity determination engine 102 is configuredto determine a change complexity of a multimedia picture relative tocomplexity associated with one or more multimedia pictures in amultimedia sequence. In an embodiment, the complexity is determinedbased on a number of bits (b) and an average quantization (Qs)associated with the multimedia picture. Also, it is noted that theterminology “average quantization” may be construed as referring to, forexample, a value or a set of values obtained during a process ofapproximating the continuous set of values in the multimedia dataassociated with the multimedia picture with a finite set of values. Theterm “average quantization” may be used interchangeably with the term“quantization scale”. With the increase in complexity of the multimediapicture, one of b and Qs for the multimedia picture increases. The b andthe Qs are inversely related, and a product of Qs and b is large forcomplex multimedia pictures when compared to simple multimedia pictures.In an embodiment, an instantaneous value of complexity of a multimediapicture is defined as the product of b and Qs.

In an embodiment, the complexity associated with a multimedia pictureincreases due to, for example, an increase in motion (e.g., a change ina scene causing a low complexity multimedia picture to be replaced witha high complexity multimedia picture), an increase in a texture contentassociated with multimedia picture, and the like. The increase in motionrequires more bits when compared to static multimedia sequences. Theincrease in the texture content of the multimedia picture may be due to,for example, multimedia panning (e.g., horizontal or vertical panning),new objects entering the multimedia sequence, and the like.

However, for heterogeneous multimedia sequences, the complexity variesfrom one multimedia picture to another, and using instantaneouscomplexity for every multimedia picture may lead to spurious complexityvariations. In an embodiment, in order to avoid the occurrence ofspurious complexity variations, a weighted average complexity isdetermined for a plurality of multimedia pictures. The weighted averagecomplexity is given by the following Equation 1:

C _(w)(n)=w*C(n)+(1−w)*C _(w)(n−1)∀n≥0  (1)

wherein w is a weight factor, C_(w)(n) and C_(w)(n−1) are the weightedaverage complexity of the multimedia pictures n and n−1, respectively,C(n) is the instantaneous complexity of the multimedia picture n, andC_(w)(−1)=0. In an embodiment, the weight factor defines an extent ofcontribution of complexity of each of the multimedia pictures to theweighted average complexity of the multimedia picture. In an embodiment,the weight factor also defines a number of multimedia picturescontributing significantly to the weighted average complexity orduration of complexity considered for determining the weighted averagecomplexity. In an embodiment, a higher value for the weight factorcorrelates to a lower number of multimedia pictures contributing to theweighted average complexity of the plurality of multimedia pictures, aswell as to a lower duration of complexity considered for determining theweighted average complexity. In an embodiment, the complexitydetermination engine 102 is configured to determine a local complexityand a global complexity associated with a multimedia picture from amongthe plurality of multimedia pictures. The local complexity is determinedover a first complexity duration and corresponds to a complexityassociated with the multimedia picture (e.g., a current multimediapicture) and one or more multimedia pictures preceding the multimediapicture (e.g., the current multimedia picture) and/or one or moremultimedia pictures succeeding the multimedia picture (e.g., the currentmultimedia picture). In an embodiment, the local complexity is aweighted average complexity of the multimedia picture, and the one ormore multimedia pictures preceding the multimedia picture and/or the oneor more multimedia pictures succeeding the multimedia picture. The localcomplexity is given by the following Equation 2:

C _(w) ^(lc)(n)=w _(1c) *C(n)+(1−w _(lc))*C _(w) ^(lc)(n−1)∀n≥0  (2)

wherein, C_(w) ^(lc)(n) and C_(w) ^(lc)(n−1) are the weighted averagelocal complexity of multimedia pictures n and n−1 of multimedia data,respectively, C(n) is the instantaneous complexity of the multimediapicture n, and w_(lc) is a weight factor corresponding to the localcomplexity based on the first complexity duration. The weight factorcorresponding to the local complexity defines an extent of contributionof complexity of each of the one or more multimedia pictures precedingthe multimedia picture and/or one or more multimedia pictures succeedingthe multimedia picture to the local complexity.

The global complexity is determined over a second complexity durationand corresponds to a complexity associated with the multimedia picture(e.g., the current multimedia picture) and at least one of a pluralityof multimedia pictures preceding the multimedia picture (e.g., thecurrent multimedia picture) and a plurality of multimedia picturessucceeding the multimedia picture (e.g., the current multimediapicture). In an embodiment, the global complexity is a weighted averagecomplexity of the multimedia picture (e.g., the current multimediapicture) and a plurality of multimedia pictures. The plurality ofmultimedia pictures includes a plurality of multimedia picturessucceeding the multimedia picture (e.g., the current multimedia picture)and/or a plurality of multimedia pictures preceding the multimediapicture (e.g., the current multimedia picture). The global complexity isgiven by the following Equation 3:

C _(w) ^(gc)(n)=w _(gc) *C(n)+(1−w _(gc))*C _(w) ^(gc)(n−1)∀n≥0  (3)

wherein, C_(w) ^(gc)(n) and C_(w) ^(gc)(n−1) are the weighted averageglobal complexity of multimedia pictures n and n−1 of the multimediadata, respectively, C(n) is the instantaneous complexity of multimediapicture n, and w_(gc) is a weight factor corresponding to the globalcomplexity based on the second complexity duration. The weight factorcorresponding to the global complexity defines an extent of contributionof each of the plurality of multimedia pictures succeeding themultimedia pictures and/or a plurality of multimedia pictures precedingthe multimedia picture. The first complexity duration may be smallerthan the second complexity duration. In an embodiment, the firstcomplexity duration is around ⅕^(th) of the second complexity duration.

In an embodiment, the weight factor corresponding to the localcomplexity is greater than the weight factor corresponding to the globalcomplexity. In an exemplary scenario, for a complexity duration of 7.5seconds, the weight factor corresponding to the local complexity is0.099 and the weight factor corresponding to the global complexity is0.023. Similarly, for a complexity duration of 1 minute, the weightfactor corresponding to the local complexity is 0.0127 and the weightfactor corresponding to the global complexity is 0.0025. It can beobserved from the exemplary scenario that the weight factorscorresponding to the local complexity and the global complexity decreasewhen there is an increase in the complexity duration.

In an embodiment, the weight factor is determined using one or moretechniques known in the art. In an embodiment, it is assumed that amultimedia picture stops contributing to the weighted average complexityonce the contribution reduces to less than x^(th) of an actualcomplexity, with x being a relatively small value (e.g., 0.01). In anembodiment, for a weight factor w, after the first multimedia picture,the contribution of a complexity C towards the weighted averagecomplexity is w*C, and after n multimedia pictures, the contribution ofa complexity C towards the weighted average complexity isw*(1−w)^((n−1))*C. For optimal performance during encoding, the weightfactor is selected such that after n multimedia pictures thecontribution of complexity of a multimedia picture should be less thanx*w*C, thereby implying that w*(1−w)^((n−1))*C is less than x*w*c andthat w is greater than 1−e^(log(x)/n−1). Hence, in an embodiment, aweight factor equal to 1−e^(log(x)/n−1) is used to ensure that thecomplexity decreases to lower than x^(th) of the actual complexity aftern multimedia pictures, with n being a particular number of multimediapictures to be considered for the complexity.

In an embodiment, the complexity determination engine 102 is configuredto compare the local complexity and the global complexity measures basedon a predetermined criterion to determine the change in the complexityof the multimedia pictures in the multimedia sequence based on thecomparison. The predetermined criterion may include, for example, thelocal complexity exceeding the global complexity by a predeterminedamount. The predetermined amount may include, for example, a product ofthe global complexity and a threshold. For example, in an embodiment,when the local complexity of the multimedia picture increases beyondtwice the global complexity then the complexity of the multimediapicture is said to be increasing. Similarly, in an embodiment, when thelocal complexity of the multimedia picture decreases below half of theglobal complexity, then the complexity of the multimedia picture is saidto be decreasing.

In an embodiment, the bit rate engine 104 is configured to adjust a bitrate for encoding the multimedia picture based on the change incomplexity of the multimedia picture. In an embodiment, the bit rateengine 104 increases the bit rate on determining an increase incomplexity of the multimedia picture and/or decreases the bit rate ondetermining a decrease in complexity of the multimedia picture. Theutilization of additional bits during a corresponding increase in thebit rate and/or saving of bits during a corresponding decrease in thebit rate is compensated by adjusting of bit rates for encodingsubsequent multimedia pictures in the multimedia sequence.

In an embodiment, the bit rate engine 104 adjusts the bit rate toachieve a predetermined target bit rate for encoding. In an embodiment,the bit rate engine 104 increases the bit rate above the predeterminedtarget bit rate when an increase in complexity of the multimedia pictureis determined. In an embodiment, the increase in the bit rate isproportional to the increase in the complexity. In an embodiment, thebit rate engine compensates the utilization of the additional bitsduring the corresponding increase in the bit rate by decreasing the bitrate upon determining a decrease in complexity of a subsequentmultimedia picture. In an embodiment, the bit rate is decreased for aduration until all additional bits consumed during the increase of thebit rate are compensated.

In an embodiment, the bit rate engine 104 decreases the bit rate belowthe predetermined target bit rate when a decrease in complexity of themultimedia picture is determined. In an embodiment, the decrease in thebit rate is proportional to the decrease in the complexity. In anembodiment, the bit rate engine 104 compensates the saving of bitsduring the corresponding decrease in the bit rate by increasing the bitrate upon determining an increase in complexity of a subsequentmultimedia picture. Adjusting the bit rate is explained further in FIG.2.

In an embodiment, the system 100 additionally includes other components(not shown in FIG. 1), such as, for example, an input unit (e.g., avideo processing device), a video display unit (e.g., liquid crystalsdisplay (LCD), a cathode ray tube (CRT), and the like), a cursor controldevice (e.g., a mouse), a drive unit (e.g., a disk drive), a signalgeneration unit (e.g., a speaker) and/or a network interface unit. Theinput unit is operable to transfer multimedia data to the complexitydetermination engine 102 and the bit rate engine 104 for the encoding ofmultimedia data. The drive unit includes a machine-readable medium uponwhich is stored one or more sets of instructions (e.g., software)embodying one or more of the methodologies and/or functions describedherein. In an embodiment, the software resides, either completely orpartially, within the memory 106 and/or within the complexitydetermination engine 102 and/or the bit rate engine 104 during theexecution thereof by the system 100 such that the memory 106, thecomplexity determination engine 102, and/or the bit rate engine 104 alsoconstitute machine-readable media.

The software may further be transmitted and/or received over a networkvia the network interface unit. The term “machine-readable medium” maybe construed to include a single medium and/or multiple media (e.g., acentralized and/or distributed database, and/or associated caches andservers) that store the one or more sets of instructions. Moreover, theterm “machine-readable medium” may be construed to include any mediumthat is capable of storing, encoding and/or carrying a set ofinstructions for execution by the system 100 and that cause the system100 to perform one or more of the methodologies of the variousembodiments. Furthermore, the term “machine-readable medium” may beconstrued to include, but shall not be limited to, solid-state memories,optical and magnetic media, and carrier wave signals.

FIG. 2 is a simplified overview of a process flow illustrating aplurality of states of operation of the system 100 of FIG. 1 accordingto an embodiment. In FIG. 2, the plurality of states of operation isrepresented by blocks 202-210. In an embodiment, the plurality of statesof operation include, but are not limited to, an average (AVG) state202, a high complexity (HIGH) state 204, a transition (AVG_TRANS) state206, a low compensating (LOW_COMP) state 208, and a low complexity(LOW_SAVE) state 210. In the AVG state 202, the multimedia pictures areencoded at a bit rate equal to a predetermined target bit rate (R). Itis noted that the terminology “bit rate” may be construed, for example,as referring to an average bit rate to be achieved over a short durationof the multimedia sequence, wherein the short duration is of the orderof a few seconds of the multimedia sequence.

The bit rate is set to a value between a minimum bit rate (R_min) and amaximum bit rate (R_max). R_max is an upper bound on the bit rate andthe R_min is a lower bound on the bit rate. Also, it is noted that theterminology “predetermined target bit rate” may be construed, forexample, as referring to a bit rate to be achieved during apredetermined duration of a multimedia sequence associated withmultimedia data during the encoding of the multimedia data. Thepredetermined duration varies from a few seconds to a few hours. Whenthe system 100 operates in the High state 204, the bit rate of encodingthe multimedia pictures is increased beyond R. Moreover, when the system100 operates in the LOW_COMP state 208, the bit rate of encoding themultimedia pictures is lower than R to thereby compensate for the excessbits consumed during HIGH state 204. Furthermore, when the system 100operates in the LOW_SAVE state 210, the bit rate of encoding is lowerthan R to thereby save bits for later use upon subsequently entering theHIGH state 204. During the AVG_TRANS state 206, the bit rate of encodingis R. The AVG_TRANS state 206 serves as a state of transition betweenthe HIGH state 204 and LOW_COMP state 208 to thereby enable a gradualtransition of bit rates during the encoding of multimedia pictures.

In an embodiment, initially, the system 100 begins operating in the AVGstate 202 with the bit rate (B) of encoding the multimedia pictures setto R. When an increase in complexity is detected (e.g., by using thecomplexity determination engine 102 of FIG. 1) at 212, the system 100transitions to the HIGH state 204 and B is increased (e.g., by using thebit rate engine 104 of FIG. 1) beyond R. The increase in B is dependentupon an amount of change in complexity between the AVG state 202 and theHIGH state 204. B is set to a value between R and R_max during the HIGHstate 204. The increase in complexity is determined if a localcomplexity (LC) increases relative to the global complexity (GC) suchthat “LC is greater than GC*TH”, where TH is a first threshold. Anexemplary value of TH includes, but is not limited to, 1.5. In anembodiment, a sensitivity factor (alpha) is used to control an amount bywhich the B is increased when transitioning to the HIGH state 204. In anembodiment, alpha is set to a value between 1.0 and R_max/R. In anembodiment, a higher value of alpha indicates a usage of a higher Bduring the HIGH state 204. During the HIGH state 204, B is increased to“R*alpha*LC/GC”.

Also, during the HIGH state 204, as B is increased, an excess number ofbits are consumed. The excess number of bits consumed is saved as B_comp(not shown in FIG. 2). Initially, during the AVG state 202, B_comp isset to 0. B_comp is updated during the HIGH state 204 to record theadditional number of bits consumed (for example, bits in addition to thenumber of bits at bit rate=R). During the HIGH state 204, B_comp isupdated to:

“B_comp+=B_current−B_target”,

where B_current is a number of bits consumed for a current multimediapicture and B_target is a target number of bits per multimedia picture.Additionally, in an embodiment, the system 100 transitions from the HIGHstate 204 to the HIGH state 204 at 214 by further increasing B, if afurther increase in the complexity is observed, such that LC increasessignificantly compared to GC. B is further increased by an amount equalto “R*alpha*LC/GC”.

In an embodiment, the complexity of the multimedia sequence issubsequently reduced such that the LC is less than GC*TL, where TL is asecond threshold. An exemplary value of TL lies between 0.875 and 1.125.At 216 it is determined whether B_comp is greater than 0. B_comp beinggreater than 0 indicates a consumption of an excess number of bitsduring the HIGH state 204. If B_comp is greater than 0, then, at 218,the system 100 transitions to the AVG_TRANS state 206 and B is reducedto R. In an embodiment, the system 100 continues to operate in theAVG_TRANS state 206 for a predetermined number of multimedia pictures(Num_trans) until a variable (Natrans) equates the Num_trans to therebyenable a gradual transition of bit rate for the encoding of multimediapictures. In an exemplary embodiment, Num_trans is set to 15. In anembodiment, if an increase in complexity of the multimedia sequence isdetermined during the AVG_TRANS state 206, such that LC is greater thanGC*TH, then, at 220, the system 100 transitions back to the HIGH state204. Furthermore, it is noted that B is increased to “R*alpha*LC/GC”.

Alternatively, at 216, if B_comp is less than 0, thereby indicating thatno additional bits are consumed during the HIGH state 204, and if thecomplexity of the multimedia sequence reduces such that the LC is lessthan GC*TH, then, at 222, the system 100 transitions to the AVG state202 from the HIGH state 204, and B is decreased to “R”.

In an embodiment, at 224, the system 100 transitions to the LOW_COMPstate 208 from the AVG_TRANS state 206 when Natrans equates to Num_transto compensate for the additional number of bits consumed during the HIGHstate 204. B is set to “R*beta*LC/GC”, where beta is a sensitivityfactor for determining an amount by which the bit rate is decreased tothereby compensate for the additional number of bits previouslyconsumed. In an embodiment, during the LOW_COMP state 208, B is set to avalue between R and R_min. The system 100 continues to operate in theLOW_COMP state 208 until all the additional bits consumed during theHIGH state 204 are compensated and such that the predetermined targetbit rate is achieved over a predetermined duration of the multimediasequence.

In an embodiment, B_comp is decremented and updated such that B_comp is“B_target−B_current”. The LOW_COMP state 208 ensures that B is notdrastically reduced. Subsequent to the operation in the LOW_COMP state208, at 226, the system 100 returns back to the AVG state 202 when acompensation has been implemented for the excess bits consumed(B_comp<0).

In an embodiment, at 228, the system 100 transitions from the LOW_COMPstate 208 to the HIGH state 204, if the complexity of the multimediasequence increases during the LOW_COMP state 208, such that LC isgreater than GC*TH, and the B is increased to “R*alpha*LC/GC”. In anembodiment, at 230, the system 100 transitions from the AVG state 202 toa LOW_SAVE state 210, by reducing the target bit rate below the averagevalue, when the complexity reduces drastically, such that LC is lessthan GC*T_ls, where T_ls is a third threshold value. An exemplary valueof T is includes, but is not limited to, 0.5. B is reduced toR*beta*LC/GC, and bits are saved up for subsequent usage in the HIGHstate 204. B_comp is updated to B_target−B_current. In an embodiment,the B is set to a value between R_min and R during the LOW_SAVE state210 and the LOW_COMP state 208. In an embodiment, the complexityincreases in the LOW_SAVE state 210 such that LC is greater than GC*Ta,where Ta is a fourth threshold value. An exemplary value of Ta liesbetween 0.6 and 0.75. In an embodiment, at 232, the system 100transitions back to the AVG state 202.

As explained earlier in the description of FIG. 1, and in accordancewith a number of exemplary scenarios, the value of weight factorscorresponding to the local complexity and the global complexitydecreases with the increase in the complexity duration. For example, fora complexity duration of 7.5 seconds, the weight factor corresponding tothe local complexity is 0.099, and the weight factor corresponding tothe global complexity is 0.023, while, for a complexity duration of 1minute, the weight factor corresponding to the local complexity is0.0127, and the weight factor corresponding to the global complexity is0.0025. As the complexity duration increases (e.g., >>1 minute), thevalues of weight factors corresponding to the local complexity and theglobal complexity further decrease.

In floating point systems, computations associated with complexity areperformed using the weight factors with at most accuracy even for verylow values of the weight factors corresponding to the local complexityand the global complexity. However, in fixed point systems, for largecomplexity durations, the computations performed using the very lowvalues of the weight factors corresponding to the local complexity andthe global complexity may tend to be inaccurate. In an embodiment, infixed point systems, fixed weight factors for a small duration on theorder of a few seconds or a few minutes are used to determine thecomplexity of multimedia pictures of large complexity durations. Themultimedia data associated with a multimedia sequence is sampled atfixed intervals, and complexities of one or more multimedia picturesassociated with the sampled multimedia data are determined using thefixed weight factors for determining change in complexity of one or moremultimedia pictures associated with the sampled multimedia data.Sampling of the multimedia data is described further in FIGS. 3A and 3B.In an embodiment, instantaneous complexities of the sampled multimediapictures may be determined. In an embodiment, a change in complexity ofone or more multimedia pictures associated with the sampled multimediadata relative to one or more multimedia pictures associated withpreviously sampled multimedia data is determined. A bit rate of encodingthe multimedia data is adjusted based on the change in complexity.

FIGS. 3A and 3B illustrate an exemplary scenario of sampling multimediadata for a large complexity duration in a fixed point system accordingto an embodiment. The large complexity duration is, for example, xminutes (e.g., >>1 minute). The multimedia data associated withmultimedia pictures are sampled at the rate of x minutes. FIG. 3Aillustrates multimedia pictures 302 a, 302 b, 302 c, 302 d, and 302 e.The multimedia pictures 302 a and 302 b are sampled at, for example, thex^(th) instant and the 2x^(th) instant, respectively. The multimediapictures 302 c and 302 d are sampled at, for example, the 4x^(th)instant and the 5x^(th) instant, respectively, and multimedia picture302 e is sampled at, for example, the 10x^(th) instant. In anembodiment, the state transitions (explained in FIG. 2) for the system100 are performed at every nx^(th) instant by sampling the multimediapictures at the rate of x and determining the complexity of themultimedia pictures sampled at every (nx)^(th) instant. The complexityof each of the sampled multimedia pictures 302 a, 302 b, 302 c, 302 d,and 302 e are determined using fixed weights factors corresponding to,for example, 1 minute. In an embodiment, the complexity duration of thefixed weight factors may be equal to the duration of each of the sampledmultimedia pictures. In an embodiment, a local complexity and a globalcomplexity for each of the sampled multimedia picture is determined.

In an exemplary scenario, a change in complexity of the multimediapictures between the two consecutively sampled multimedia pictures isneglected if the change is minimal. In multimedia pictures, where thechange in complexity of the multimedia pictures between the twoconsecutively sampled multimedia pictures is not negligible, an averagecomplexity of multimedia pictures in between the two consecutivelysampled multimedia pictures is considered to determine the change incomplexity of the sampled multimedia pictures for transitioning tovarious states. In an embodiment, the average complexity corresponds toan average value of complexity of a plurality of multimedia pictures andthe sampled multimedia picture, wherein the plurality of multimediapictures includes a plurality of multimedia pictures preceding thesampled multimedia picture and/or succeeding a previously sampledmultimedia picture. The average complexity is determined to determinethe change in complexity of the sampled multimedia picture relative tocomplexity associated with one or more multimedia pictures in themultimedia sequence. The average complexity for an nx^(th) multimediapicture is given by the following Equation 4:

$\begin{matrix}{C_{nx} = {\left( \frac{1}{x} \right){\underset{i = {{{({n - 1})}x} + 1}}{\sum\limits^{nx}}C_{i}}}} & (4)\end{matrix}$

where C_(nx) is the average complexity of “n” multimedia pictures andC_(i) is the complexity associated with a multimedia picture i, with ibeing a positive integer and x corresponding to the duration of thecomplexity.

FIG. 3B illustrates multimedia pictures 302 f, 302 g, 302 h, and 302 i,which are sampled at consecutive (nx)^(th) instances. In an embodiment,the complexity of multimedia picture 302 i is determined (e.g. usingcomplexity determination engine 102 of FIG. 1) based on an average valueof complexity of multimedia pictures 302 j, 302 k and one or moreintermediate multimedia pictures (not shown in FIG. 3B) up to themultimedia picture 302 i. In an embodiment, a change in complexity ofthe multimedia picture 302 i relative to complexity associated with themultimedia pictures 302 j, 302 k is determined based on the complexityof the multimedia picture 302 i.

According to various embodiments, the system 100 disclosed hereinenables optimal utilization of bits for encoding multimedia data byachieving a predetermined target bit rate over a predetermined durationof the multimedia sequence, thereby maximizing a perceptual multimediaquality. The perceptual multimedia quality is assessed based on visibleartefacts caused by degradation of decoded multimedia data due to theencoding or decoding processes.

FIG. 4 illustrates exemplary bit rate traces for the encoding ofmultimedia data pursuant to an exemplary scenario. A bit rate trace is aplot of a variation in a number of bits consumed during the encoding ofa plurality of pictures corresponding to the multimedia data. In FIG. 4,a reference index of pictures corresponding to the multimedia is plottedon the X-axis 402, and the corresponding number of bits consumed isplotted on the Y-axis 404. In FIG. 4, a first bit rate trace 406corresponds to a scenario where a bit rate is maintained at apredetermined target bit rate (for example, a predetermined average bitrate) irrespective of the change in complexity of the pictures beingencoded. A second bit trace 408 corresponds to a scenario where a bitrate is adjusted based on a determined change in complexity of thepictures corresponding to the multimedia data (for example, by system100 as explained in FIGS. 1 and 2). In an embodiment, the bit tracedepicted in FIG. 4 may correspond to multimedia data, such as a videosurveillance sequence for a surveillance application. In an embodiment,a predetermined target bit rate trace is 500 kilobits per second (kbps).

In FIG. 4, a utilization of a higher number of bits for encoding isobserved from picture ref #240 to picture ref #300, which may correspondto a high activity period 410. No other activity is observed in themultimedia data barring the high activity period 410 from picture ref#240 to picture ref #300. In an embodiment, the high activity period 410may correspond to an instance of a person walking across a videosurveillance camera capturing the surveillance data.

Since there is no activity from picture ref #100 to picture ref #239,the first bit trace 406 and the second bit rate trace 408 follow similarplots, thereby indicating a utilization of an average bit rate ofencoding of the multimedia data. The period of operation from pictureref #100 to picture ref #239 corresponds to an average activity period412. The average activity period 412 corresponds to the AVG state 202 ofoperation of the system 100, as explained in FIG. 2. When a complexitycorresponding to the multimedia data begins to increase at picture 240(as a result of an increase in activity), the second bit rate trace 408indicates a transition to a higher bit rate than the predeterminedtarget bit rate (for example, a transition to the HIGH state 204 fromthe AVG state 202 of system 100), whereas the first bit rate trace 406is maintained at the predetermined target bit rate.

After the activity ceases (with the corresponding decrease incomplexity) at picture ref #300, the first bit rate trace 408 indicatesa transition to a lower bit rate than the predetermined target bit rate(for example, a transition to the LOW_COMP state 208 from the HIGH state204 of system 100). The lower bit rate is maintained until picture 465,wherein a compensation is implemented for all of the excess number ofbits utilized during the transition to the higher bit rate. The periodof operation from picture ref #300 to picture ref #465 corresponds to alow activity period 414. It is noted that a number of bits consumed frompicture ref #300 to picture ref #465 for the second bit rate trace 408are less than the number of bits consumed over the same period for thefirst bit trace 406. The predetermined target bit rate of encoding isutilized for the second bit trace 408 from picture ref #465 onwards thatcorresponds to the average activity period 412 (for example, atransition to the AVG state 202 from the LOW_COMP state 208 of system100). Adjusting the bit rate based on a change in complexity of amultimedia picture relative to complexity associated with one or moremultimedia pictures in a multimedia sequence may improve a perceptualquality of the multimedia data. This is further illustrated in FIGS.5A-5D.

FIG. 5A illustrates peak signal to noise ratio (PSNR) tracescorresponding to the first bit rate trace 406 and the second bit ratetrace 408 of FIG. 4 according to an embodiment. A PSNR trace is a plotof PSNR observed across a plurality of pictures corresponding to themultimedia data. In FIG. 5A, a reference index of pictures correspondingto the multimedia is plotted on the X-axis 502 a, and the correspondingPSNR is plotted on the Y-axis 502 b. In FIG. 5A, a PSNR trace 504corresponds to a plot of variation in PSNR observed for a bit rate ofencoding corresponding to the first bit rate trace 406, and a PSNR trace506 corresponds to a plot of variation in PSNR observed for a bit rateof encoding corresponding to the second bit rate trace 408.

It can be observed that the PSNR trace 506 corresponding to the secondbit rate trace 408 achieves a significantly higher PSNR in the durationof higher activity (e.g., picture ref #240-300) when compared to thePSNR trace 504 corresponding to the first bit rate trace 406. A PSNRdrop to 33 dB is observed for the PSNR trace 504 in the high activityperiod 410. The PSNR stays above 38 dB for the PSNR trace 502 during thehigh activity duration 410. As illustrated in FIG. 5A, the encodingperformed by adjusting the bit rate based on the determined change incomplexity of the pictures (for example, by using system 100) improvesthe PSNR, and, hence, perceptual multimedia quality is improved.

FIG. 5B illustrates difference mean opinion score (DMOS) tracescorresponding to the first bit rate trace 406 and the second bit ratetrace 408 of FIG. 4 according to an embodiment. A DMOS trace is a plotof DMOS observed across a plurality of pictures corresponding to themultimedia data. In FIG. 5B, a reference index of pictures correspondingto the multimedia is plotted on the X-axis 512 a and the correspondingPSNR is plotted on the Y-axis 512 b. In FIG. 5B, a DMOS trace 514corresponds to a plot of variation in DMOS observed for a bit rate ofencoding corresponding to the first bit rate trace 406, and a DMOS trace516 corresponds to a plot of variation in DMOS observed for a bit rateof encoding corresponding to the second bit rate trace 408.

It can be observed that the DMOS trace 516 corresponding to the secondbit rate trace 408 achieves significantly lower DMOS in the duration ofhigher activity (e.g., picture ref #240-300) when compared to the DMOStrace 514 corresponding to the first bit rate trace 406. In case of aDMOS trace, lower DMOS values indicate better perceptual multimediaquality. As illustrated in FIG. 5B, the encoding performed by adjustingthe bit rate based on the determined change in complexity of thepictures (for example, by using system 100) improves the DMOS, and,hence, perceptual multimedia quality is improved.

FIG. 5C illustrates a plot of variation in PSNR for a plurality of bitrates for (1) a scenario where a bit rate is maintained at apredetermined target bit rate irrespective of the change in complexityof pictures being encoded and (2) a scenario where a bit rate isadjusted based on a determined change in complexity of the picturescorresponding to the multimedia data according to a embodiment. In FIG.5C, a bit rate (measured in kbps) is plotted on the X-axis 522 a and thecorresponding PSNR (measured in decibels) is plotted on the Y-axis 522b. In FIG. 5C, a plot 524 corresponds to a plot of variation in PSNR fora plurality of bit rates for a scenario where a bit rate is maintainedat a predetermined target bit rate irrespective of the complexity ofpictures being encoded, and a plot 526 corresponds to a plot ofvariation in PSNR for a plurality of bit rates for a scenario where abit rate is adjusted based on a determined change in complexity of thepictures corresponding to the multimedia data. As illustrated in FIG.5C, for the bit rates ranging from 200 to 500, the PSNR is improved bymore than 0.3 dB for all bit rates for plot 526 as compared to plot 524.

FIG. 5D illustrates a plot of variation in DMOS for a plurality of bitrates for (1) a scenario where a bit rate is maintained at apredetermined target bit rate irrespective of change in complexity ofpictures being encoded and (2) a scenario where a bit rate is adjustedbased on a determined change in complexity of the pictures correspondingto the multimedia data according to a embodiment. In FIG. 5D, a bit rate(measured in kbps) is plotted on the X-axis 532 a, and the correspondingDMOS is plotted on the Y-axis 532 b. In FIG. 5D, a plot 534 correspondsto a plot of variation in DMOS for a plurality of bit rates for ascenario where a bit rate is maintained at a predetermined target bitrate irrespective of the complexity of pictures being encoded, and aplot 536 corresponds to a plot of variation in DMOS for a plurality ofbit rates for a scenario where a bit rate is adjusted based on adetermined change in complexity of the pictures corresponding to themultimedia data. As illustrated in FIG. 5D, an overall DMOS is loweredby more than 20 at 200 kbps for plot 536 as compared to plot 534. Thus,FIGS. 5A-5D illustrate that a perceptual multimedia quality is improvedwhen a bit rate is adjusted based on a change in complexity of a picturecorresponding to multimedia data as compared to a scenario where a bitrate is maintained at a predetermined target bit rate irrespective ofvariations in complexity of the pictures.

FIG. 6 is a flow chart 600 of a method of bit rate control duringencoding multimedia data associated with a multimedia picture accordingto an embodiment. Examples of multimedia data include, but are notlimited to, video data, and the like. The multimedia picture may beassociated with a multimedia sequence. Each multimedia sequence mayinclude one or more multimedia pictures. An example of a multimediasequence is a collection of consecutive multimedia pictures with allmultimedia pictures in the multimedia sequence belonging to the same ordifferent scene. As illustrated in FIG. 6, in operation 602, a localcomplexity and a global complexity associated with the multimediapicture in a multimedia sequence is determined. The local complexity isdetermined over a first complexity duration and corresponds to acomplexity associated with the multimedia picture (e.g., a currentmultimedia picture) and one or more multimedia pictures preceding themultimedia picture (e.g., the current multimedia picture) and/or one ormore multimedia pictures succeeding the multimedia picture (e.g., thecurrent multimedia picture). The global complexity is determined over asecond complexity duration and corresponds to a complexity associatedwith the multimedia picture and a plurality of multimedia picturespreceding the multimedia picture and/or a plurality of multimediapictures succeeding the multimedia picture. In an embodiment, the firstcomplexity duration is smaller than the second complexity duration. Inan embodiment, the local complexity and/or the global complexity isdetermined based on a number of bits and an average quantizationassociated with the multimedia picture. In an embodiment, the localcomplexity and the global complexity may be calculated by usingEquations 2 and 3 respectively, which are explained above with referenceto FIG. 1. In an embodiment, a first weight factor corresponding to thelocal complexity and a second weight factor corresponding to the globalcomplexity are determined. The first weight factor is determined basedon the first complexity duration and defines an extent of contributionof the complexity of each of the one or more multimedia picturespreceding the multimedia picture and/or one or more multimedia picturessucceeding the multimedia picture to the local complexity. The secondweight factor is determined based on the second complexity duration anddefines an extent of contribution of the complexity of each of theplurality of multimedia pictures preceding and/or succeeding themultimedia picture to the global complexity.

In an embodiment, in operation 604, the local complexity is comparedwith the global complexity based on a predetermined criterion todetermine a change in complexity of the multimedia picture relative tocomplexity associated with one or more multimedia pictures in themultimedia sequence. The predetermined criterion may include, forexample, the local complexity exceeding the global complexity by apredetermined amount (e.g., LC>GC*TH as described above with referenceto FIG. 2). The predetermine amount may include, for example, a productof the global complexity and a threshold (e.g., a first threshold TH, asecond threshold TL, a third threshold T_ls, and a fourth threshold Tawith reference to description of FIG. 2). For example, in an embodiment,when the local complexity of the multimedia picture increases beyondtwice the global complexity then the complexity of the multimediapicture is said to be increasing. Similarly, in an embodiment, when thelocal complexity of the multimedia picture decreases below half of theglobal complexity, then the complexity of the multimedia picture is saidto be decreasing.

In an embodiment, in order to encode large complexity durations (of theorder of a few minutes to a few hours) in fixed point systems,multimedia data associated with multimedia pictures are sampled at apredetermined rate. The sampling of the multimedia pictures in fixedpoint systems is as described in the description of FIGS. 3A-3B. Thecomplexity of the multimedia pictures associated with the sampledmultimedia data is determined based on a predetermined weight factor fora predetermined complexity duration. In an embodiment, the complexitycorresponds to an instantaneously determined complexity of the sampledmultimedia data. In an embodiment, a change in complexity of one or moremultimedia pictures associated with the sampled multimedia data relativeto one or more multimedia pictures associated with previously sampledmultimedia data is determined. A bit rate of encoding the multimediadata is adjusted based on the change in complexity.

In an embodiment, during instantaneously determining the complexity,change in complexity of the multimedia pictures between the twoconsecutively sampled multimedia pictures is neglected if the change isminimal. In multimedia sequences where the change in complexity of themultimedia pictures between the two consecutively sampled multimediapictures is not negligible, an average complexity of multimedia picturesin between the two consecutively sampled multimedia pictures isconsidered to determine the change in complexity of the sampledmultimedia pictures when transitioning to various states. In anembodiment, the complexity corresponds to an average value of complexityof a plurality of multimedia pictures and the sampled multimedia data.In an embodiment, the plurality of multimedia pictures includes aplurality of multimedia pictures preceding the sampled multimedia dataand/or succeeding a previously sampled multimedia data (such asexplained in FIG. 3B). In an embodiment, a change in complexity of oneor more multimedia pictures associated with the sampled multimedia datarelative to one or more multimedia pictures associated with previouslysampled multimedia data is determined based on the determined averagevalue of complexity and a bit rate for encoding the multimedia data isadjusted based on the change in complexity.

In an embodiment, in operation 606, a bit rate for encoding themultimedia picture is adjusted based on the change in complexity of themultimedia picture. In an embodiment, the bit rate is adjusted byperforming one of increasing the bit rate and decreasing the bit rate.In operation 606 a, the bit rate is increased on determining an increasein complexity of the multimedia picture. Alternatively, in operation 606b, the bit rate is decreased on determining a decrease in complexity ofthe multimedia picture. The utilization of additional bits during acorresponding increase in the bit rate and/or saving of bits during acorresponding decrease in the bit rate is compensated during adjustingof bit rates for encoding subsequent multimedia pictures in themultimedia sequence.

In an embodiment, the bit rate is adjusted to achieve a predeterminedtarget bit rate for encoding multimedia data. It is noted that theterminology “bit rate” may be construed as referring to, for example, anaverage bit rate to be achieved over a short duration of the multimediasequence, wherein the short duration is of the order of a few seconds ofthe multimedia sequence. The bit rate is set to a value between aminimum bit rate (R_min) and a maximum bit rate (R_max). R_max is anupper bound on the bit rate and R_min is a lower bound on the bit rate.Also, it is noted that the terminology “predetermined target bit rate”may be construed as referring to, for example, a bit rate to be achievedduring a predetermined duration of a multimedia sequence associated withmultimedia data during the encoding of the multimedia data. Thepredetermined duration varies from a few seconds to a few hours. In anembodiment, the bit rate is increased above a predetermined target bitrate upon determining an increase in complexity of the multimediapicture, wherein the increase in the bit rate is proportional to theincrease in the complexity. The utilization of the additional bitsduring corresponding increase in the bit rate is compensated bydecreasing the bit rate upon determining a decrease in complexity of asubsequent multimedia picture. The bit rate is decreased for a durationuntil all additional bits consumed during the increase of the bit rateare compensated.

Also, in an embodiment, the bit rate is decreased below thepredetermined target bit rate upon determining a decrease in complexityof the multimedia picture. The decrease in the bit rate is proportionalto the decrease in the complexity. The saving of bits during thecorresponding decrease in the bit rate is compensated by increasing thebit rate upon determining an increase in complexity of a subsequentmultimedia picture. The saved bits are utilized during a subsequentincrease in the complexity of the multimedia pictures. Adjusting the bitrate may be carried out, for example, as explained above in thedescription of FIG. 2.

Although the present technology has been described with reference tospecific exemplary embodiments, it is noted that various modificationsand changes may be made to these embodiments without departing from thebroad spirit and scope of the present technology. For example, thevarious devices, modules, analyzers, generators, etc., described hereinmay be enabled and operated using hardware circuitry (e.g.,complementary metal oxide semiconductor (CMOS) based logic circuitry),firmware, software and/or any combination of hardware, firmware, and/orsoftware (e.g., embodied in a machine readable medium). For example, thevarious electrical structures and methods may be embodied usingtransistors, logic gates, and electrical circuits (e.g., applicationspecific integrated circuit (ASIC) circuitry and/or in Digital SignalProcessor (DSP) circuitry).

Particularly, in the system 100, the complexity determination engine 102and the bit rate engine 104 of FIG. 1 may be enabled using softwareand/or using transistors, logic gates, and electrical circuits (e.g.,integrated circuit circuitry such as ASIC circuitry).

Embodiments of the present disclosure include one or more computerprograms stored or otherwise embodied on a computer-readable medium,wherein the computer programs are configured to cause a processor toperform one or more operations. A computer-readable medium storing,embodying, or encoded with a computer program, or similar language, maybe embodied as a tangible data storage device storing one or moresoftware programs that are configured to cause a processor to performone or more operations. Such operations may be, for example, any of thesteps or operations described herein. Additionally, a tangible datastorage device may be embodied as one or more volatile memory devices,one or more non-volatile memory devices, and/or a combination of one ormore volatile memory devices and non-volatile memory devices.

Also, techniques, devices, subsystems and methods described andillustrated in the various embodiments as discrete or separate may becombined or integrated with other systems, modules, techniques, ormethods without departing from the scope of the present technology.Other items shown or discussed as directly coupled or communicating witheach other may be coupled through some interface or device, such thatthe items may no longer be considered directly coupled to each other butmay still be indirectly coupled and in communication, whetherelectrically, mechanically, or otherwise, with one another. Otherexamples of changes, substitutions, and alterations ascertainable by oneskilled in the art, upon studying the exemplary embodiments disclosedherein, may be made without departing from the spirit and scope of thepresent technology.

It should be noted that reference throughout this specification tofeatures, advantages, or similar language does not imply that all of thefeatures and advantages should be or are in any single embodiment.Rather, language referring to the features and advantages may beunderstood to mean that a specific feature, advantage, or characteristicdescribed in connection with an embodiment may be included in at leastone embodiment of the present technology. Thus, discussions of thefeatures and advantages, and similar language, throughout thisspecification may, but do not necessarily, refer to the same embodiment.

Various embodiments of the present disclosure, as discussed above, maybe practiced with steps and/or operations in a different order, and/orwith hardware elements in configurations which are different than thosewhich are disclosed. Therefore, although the technology has beendescribed based upon these exemplary embodiments, it is noted thatcertain modifications, variations, and alternative constructions may beapparent and well within the spirit and scope of the technology.

Although various exemplary embodiments of the present technology aredescribed herein in a language specific to structural features and/ormethodological acts, the subject matter defined in the appended claimsis not necessarily limited to the specific features or acts describedabove. Rather, the specific features and acts described above aredisclosed as exemplary forms of implementing the claims.

What is claimed is:
 1. A system comprising: a first operating statehaving a first bit rate; a second operating state having a second bitrate greater than the first bit rate; a complexity determination engineconfigured to determine an increase in complexity of a bit stream of avideo sequence; and a processor configured to: transition the systemfrom the first operating state to the second operating state in responseto the complexity determination engine determining the increase incomplexity of the bit stream; and in response to the complexitydetermination engine determining a decrease in the complexity of the bitstream while in the second operating state: transition the system fromthe second operating state to the first operating state in response toan excess bit rate less than a threshold; and transition the system fromthe second operating state to a third operating state in response to theexcess bit rate above the threshold.
 2. The system of claim 1, wherein:the increase in complexity is determined when a local complexityincreases relative to a global complexity.
 3. The system of claim 1,wherein: a sensitivity factor controls the transition from the firstoperating state to the second operating state.
 4. The system of claim 1,further comprising: a bit rate engine configured to increase the firstbit rate to the second bit rate in response to the system transitioningfrom the first operating state to the second operating state.
 5. Thesystem of claim 1, further comprising: a bit rate engine configured todecrease the second bit rate to the first bit rate in the thirdoperating state.
 6. The system of claim 1, wherein: the processor isconfigured to transition the system from the third operating state to afourth operating state in response to a number of pictures of the videosequence above a second threshold.
 7. The system of claim 6, wherein:the system operates in the fourth operating state until excess bitsconsumed during the second operating state are compensated and apredetermined target bit rate is achieved over a predetermined durationof the video sequence.
 8. The system of claim 7, wherein: the processoris configured to transition the system from the fourth operating stateto the first operating state in response to the excess bits consumedduring the second operating state are compensated and the predeterminedtarget bit rate is achieved over the predetermined duration of the videosequence.
 9. The system of claim 1, wherein: the processor is configuredto transition the system from the first operating state to a fifthoperating state in response to the complexity of the bit stream reducesbelow a third threshold.
 10. The system of claim 9, wherein: theprocessor is configured to transition the system from the firstoperating state to the fifth operating state by reducing a target bitrate below the first bit rate.
 11. A non-transitory computer-readablemedium comprising instructions that, when executed, cause a computer to:determine a complexity determination of a bit stream; transition a firstoperating state to a second operating state in response to an increasein the complexity determination; and in response to a decrease in thecomplexity determination while in the second operating state: transitionfrom the second operating state to the first operating state in responseto an excess bit rate less than a threshold; and transition from thesecond operating state to a third operating state in response to theexcess bit rate above the threshold.
 12. The computer-readable medium ofclaim 11, wherein: the increase in complexity is determined when a localcomplexity increases relative to a global complexity.
 13. Thecomputer-readable medium of claim 11, wherein: a sensitivity factorcontrols the transition from the first operating state to the secondoperating state.
 14. The computer-readable medium of claim 11,comprising further instructions that, when executed, cause the computerto: increase a first bit rate to a second bit rate in response totransitioning from the first operating state to the second operatingstate.
 15. The computer-readable medium of claim 11, comprising furtherinstructions that, when executed, cause the computer to: decrease asecond bit rate to a first bit rate in the third operating state. 16.The computer-readable medium of claim 11, comprising furtherinstructions that, when executed, cause the computer to: transition fromthe third operating state to a fourth operating state in response to anumber of pictures of a video sequence above a second threshold.
 17. Thecomputer-readable medium of claim 16, comprising further instructionsthat, when executed, cause the computer to: transition from the fourthoperating state after excess bits consumed during the second operatingstate are compensated and a predetermined target bit rate is achievedover a predetermined duration of the video sequence.
 18. Thecomputer-readable medium of claim 17, comprising further instructionsthat, when executed, cause the computer to: transition from the fourthoperating state to the first operating state in response to the excessbits consumed during the second operating state are compensated and thepredetermined target bit rate is achieved over the predeterminedduration of the video sequence.
 19. The computer-readable medium ofclaim 11, comprising further instructions that, when executed, cause thecomputer to: transition from the first operating state to a fifthoperating state in response to the complexity of the bit stream reducesbelow a third threshold.
 20. The computer-readable medium of claim 19,comprising further instructions that, when executed, cause the computerto: transition from the first operating Mate to the fifth operatingstate by reducing a target bit rate below a first bit rate.